Assistant Commissioner John Yates said more resources had been targeted at neo-Nazis because of fears of attacks and warned of bombers operating alone and without an organised network behind them.

Mr Yates told the Commons Home Affairs Committee: 'What we have seen in recent years is a growth around some of the far-right extremism movements.

'Mostly they tend to be less organised, you tend to see the concept of the lone wolf.

'There have been several manifestations of that in past months and several arrests.

'That is something we take extremely seriously and we make sure we balance our resources to deal with that threat.'

His response came to a question from Labour MP David Winnick who asked him about racist and fascist groups who turned to violence.

This summer the so-called 'Bedroom Bomber', Neil Lewington from Reading, was convicted of planning a racist terror campaign on the streets of Britain.

The Old Bailey heard he wanted to emulate his far-right heroes, Oklahoma bomber Timothy McVeigh and Soho nail bomber David Copeland.

His plotting was uncovered by chance when he was arrested for drunkenly abusing a train conductor and officers found he was carrying bomb parts.

Officers in West Yorkshire recently foiled an international plot to put guns and explosives in the hands of violent bigots in Britain.

At least 32 people were quizzed and 22 addresses searched across the North of England in April and May.

Mr Yates also told the committee of the danger of terrorists targeting Christmas shoppers in major shopping areas and outdoor markets in the run up to the festive season. More officers would be targeted at threat areas depending on intelligence, he said.